Critical of Co-Workers

For the last few weeks, I’ve had a pretty negative attitude at work. My thoughts about my co-workers are critical and judgmental. It’s very much a manual issue because I think they should be doing things differently. There are models, systems, and standards by which our company operates and yet several of my co-workers aren’t performing to these standards. I’m aware of these thoughts, but I’m having a hard time latching onto anything neutral, let alone positive. Obviously my negative attitude is having zero effect on how they perform. And my negative attitude is making me miserable and giving me headaches. Clearly no upside. What steps can I take to let go and stop being so critical?